The access policy asks who the caller is, and until now only a bearer token
could answer. That is what a desktop client carries — but a person clicking a
download link on the site carries a session instead, and the engine has no idea
what a session is. So a host that gated its catalog found its own signed-in
visitors refused at /api/download, which is a regression the shadowed route used
to hide.
c.subject_resolver is a callable taking the Rack request and returning the
host's subject: `->(request) { request.env["warden"]&.user }` for a Devise app.
Unset — every deployment today — a non-bearer request stays anonymous, exactly
as before. A resolver that raises is logged and treated as anonymous, because a
broken one turning every read into a 500 is worse than an anonymous request.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>